Introduction
Soft tissue sarcomas (STS) are a heterogeneous group of cancerous tumors, comprised of more than 50 histological subtypes that develop from soft tissues of the body (eg, fat, muscles, nerve tissue, deep skin tissue, visceral nonepithelial tissue). Due to many factors, not limited to the heterogeneity of this set of diseases and lack of screening tests, reaching a diagnosis of STS is challenging for the general practitioner as well as for the oncologist. Sarcomas may present with nonspecific and often indolent symptomology, depending on the specific histological subtype. According to the American Cancer Society, the signs and symptoms of a sarcoma include a new or growing lump, worsening abdominal pain, blood in stool or vomit, and black stools (due to abdominal bleeding).1 Unfortunately, these symptoms could be indicative of any number of other health conditions and are nonspecific to sarcoma.
As with many cancers, the early detection of disease when it may be completely resected could lead to a cure, whereas diagnosis when the disease is no longer amenable to surgery will impact patient survival. Among all forms of STS, early diagnosis when the patient has only localized disease is associated with an 80.8% five-year survival rate, which decreases to 16.4% for patients whose disease has already metastasized to other parts of the body at the time of diagnosis.2
Previous work has evaluated the relationship between duration of symptoms that may lead to a diagnosis of sarcoma and cancer outcomes. A retrospective analysis of a cohort of adults with bone or STS found no correlation between patient recall of duration of prediagnosis symptoms and survival or metastatic disease at diagnosis.3,4 Little other research was identified that examined the challenges of identifying a potential sarcoma. Despite the gap in knowledge, advocacy and patient-centered organizations emphasize the risk of delayed diagnosis and report high levels of stress and frustration among patients by the time an accurate diagnosis is obtained.5 The objective of this study was to quantify the health care experience and misdiagnoses that occurred prior to a sarcoma diagnosis compared to a cohort of matched controls.
Methods
A retrospective observational database study was conducted using detailed resource utilization and cost data from the Truven MarketScan claims database. Truven MarketScan® is a HIPAA-compliant, fully integrated patient-level database containing inpatient, outpatient, drug, lab, health risk assessment, and benefit design information from commercial and Medicare supplemental insurance plans. Additionally, the Health and Productivity Management (HPM) database, containing workplace absence, short-term disability, long-term disability, and worker’s compensation data, is linked at the individual patient level. The linkage of the claims and HPM database was used for this study.
Patients were eligible for inclusion in the cohort of a sarcoma if they had at least two ICD-9 codes of 171.x on two different days between July 1, 2004, and March 30, 2014. The date of the first eligible code was considered the index date. Patients were required to have at least 6 months of health care plan enrollment prior to the first eligible ICD-9 code to allow for prediagnosis activity to be identified in the database. Patients were also required to be 18 years of age or older on the first eligible ICD-9 code date. Patients were excluded who had evidence suggesting a diagnosis of osteosarcoma, Kaposi’s sarcoma, or gastrointestinal stromal tumors (treatment with methotrexate, ICD-9 codes of 176.x, 171.x, or 238.1), a history of any cancer before the eligible sarcoma ICD-9 code, or history of systemic anticancer therapy during the 6-month pre-index period. All patients meeting eligibility criteria were included in the matching algorithm to identify the control cohort.
The matched control cohort was required to have at least the same duration of follow-up at the case level as the matched sarcoma patient, could not have any evidence of any malignancy at any time in the database, nor could have received any systemic anticancer therapy at any time. Controls were randomly selected from the more than 100 million individual patient cases in the MarketScan database to be matched to the eligible sarcoma patient cohort exactly on age, geographic region of residence, health insurance plan type, gender, noncancer comorbid conditions (measured by Charlson Comorbidity Index items), and employment status. All factors were exact matched at the sarcoma cohort index diagnosis date. In the case of missing variables, patients were matched on missingness (eg, a case with missing employment status would be matched to a control with missing employment status).
The eligible time period for the index date of the possible sarcoma cohort and matched controls was between July 1, 2004, and March 30, 2014, which allowed for a minimum of 1-year follow-up through the end of the database available at the time of analysis.